Sand-blast apparatus.



G. A. DREISBAGH.

SAND BLAST APPARATUS.

APPLICATION FILED MAY 10, 1913.

, 1,093,551 Patentd Ap1 .14,1914.

air

'A carton.

CHARLES A. DREISBACH, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO NEW HAVEN SAND BLAST COMPANY, OF NEW HAVEN, CONNECTICUT, A CORPORATION OF CON- N ECTICUT.

SAND-BLAST APPARATUS.

Specification of Letters Patent.

Patented Apr. 14, 121.4%.

Application filed May 10, 1913. Serial No. 766,854.

apparatus in which the sand is fed from a" stationary hopper into, a mixing chamber through which a blast of air is forced, the sand being carried from the mixing chamber by the blast 'and led through a flexible hose to the point at which it is discharged against the objects such as large castings which are under treatment.

The object of my invention is to provide an improved air and sand mixing chamber,

the feedof the sand to which is so arranged that it automatically stops very shortly af ter the blast is shut 011', thus preventing the accumulation of a large quantity of sand in the mixing chamber and the disadvantageous results which accompany the latter.

In the illustrative drawings herewith,

Figure 1 is a longitudinal vertical section,

showing portions of the apparatus in elevation; on line 1-1, Fig. 2; Fig. 2 is a transverse vertical section on the line 2-2, Fig. 1; but showing the valves 28 open; Fig. 3 is a perspective of the casting which forms the mixing chamber; and Fig. 4 is-a similar view of the regulating valve.

In sand blast apparatus of the present type it is customary to provide a mixing chamber which has a side inlet for the blast and a top inlet for the sand, the latter being.

caught by the blast as it falls into orvis sucked into the box. When the blast is shut off at the nozzle, as it frequentlyis, the feed of sand into the mixing box continues by gravity, with the result that the mixing box fills up and when the blast is again freed the accumulated sand in the mixing box is forced in a body into the hose. Inasmuch as there is ordinarily a bendin the hose at or near the point of attachment to the box, the accumulated sand coming out in a substantially solid body impinges against the hose and has a very severe wearing action thereon, as well aS giving a sadden and undesirably richflow of sand at the 5 discharge end of the hose. I now propose to so construct the mixing chamber that this accumulation of sand, during the temporary halt of the apparatus, is prevented, and to this end I substitute for the "usual top feed port a'lateral feed port through which the sand enters the mixing chamber, the port being so arranged that the gravity .feed of the sand is automatically choked by the slight amount of sand which flows in by gravity after the blast is stopped. Prefer ably the lateral feed port is so arranged with relation to the blast inlet and outlet ports, that the sand accumulating during the halt of the blast, does not rise above the lower portion of the blast inlet and outlet ports. Consequently when the blast is again turned sand and picks it up gradually instead .of blowing it. as a mass, ,into the hose. Not only is the wear on the hose thus materially on it sweeps over the surface of the decreased, but the flow of sand at the discharge end of the hose is made more even than heretofore. l

In'the particular embodiment of' my inventionherewith illustrated, I have shown the feed box 10 arranged below the sand hopper 11 and communicating therewith through the opening 12 in the top of the feed box. .The flange 13 at the top of the box-aiiords means for rigidly mounting the S tops of the ports 17 may be inclined as at 18,

to the angle which the surface of the sand S willtake as it flows in by gravity after the blast has been halted. The top of the casting may be gabled, as at 19, to guide the flow. of sand equally to opposite sides of the casting. The blast pipe 20 opens through the box to the mixing chamber level of the sand which can accumulate in the mixing chamber. So, the discharge port 22 lies at least in its major portion, above the level of the accumulated sand.

The dischar e ort 22 o ens to a nozzle 23 a 0 at the port 21 the upper portion of which lies above the a at the outer end of which the flexible hose 24 is attached. The flange 25 by which the nozzle is bolted to the box overlies the sides of the casting 14 and thus serves' to hold the latter in position in the seat 26 recessed into the opposite wall of the mixing box. The large end of the passage 27 in the nozzle forms a sort of expansion chamber for the blast emerging from the port 22 and a whirling action is obtained here which insures an auxiliary thorough mixture of the air with the sand before the blast emerges from the nozzle and enters the flexible tub- While the automatic throttle of the ports 17 by the sand is suflicient to prevent the undue accumulation of sand in the mixing chamber, I propose to furnish also a pair of slide valves 28 arranged within the mixing chamber 15 and connected by a web 29 to which the valve stem 30 is attached, passing out through the boss 31 on the rear of the feed box. By sliding these valves forward the fiow of sand to the mixing chamber may be entirely stopped or it can be regulated to admit a greater or less quantity of sand as 1ISnay be desired during the operation of the last.

The operation of the apparatus is readily understood. Assuming the blast to be in use, the flow of air through the mixing chamber is suflicient to take up the sand fed by gravity thereto through the ports 17 and if under suflicient head, to increase this feed by suction. If the blast is cut off, and the valves 28 are left open, the sand continues to feed by gravityinto the chamber 15 until its feed ports are choked by the accumulated sand. This chokingis efi'ected before the accumulated sand reaches the upper level of the inlet and discharge ports 21, 22, for the blast, or so as to materially obstruct them. Thus when the blast is released, it blows over the surface of the sand and picks it up gradually, instead of blowing it en masse into the tubing. The thorough mixture of the air and sand is augmented by the expansion of the air and the whirling action caused by the enlargement of the end of the nozzle adjacent the mixing chamber, while the "fact that the flexible hose is attached at a distance' of eight or ten inches from the mixing chamber and after a thorough mixture of the sand and air has taken place, protects it to a large extent against theerosive action of the sand.

The construction shown is but a single exemplary embodiment of my invention, in

. which many modifications of construction which accomplish the same result, will read ily suggest themselves.

I am aware that it has previously been proposed to feed sand to a blast from an overhead supply in such manner that the sand falling by gravity through the sand feed hole forms a cone which gradually grows in height until its top plugs the feed hole, and I make no claim to such an arrangement.

V I claim as my invention 1. In a sand blast apparatus, a sand feed box adapted to receive sand from a superposed hopper, a mixing chamber within said feed box, passages opening from the feed box through the sides of said mixing chamber to admit sand by gravity to the latter, together with blast inlet and outlet ports opening to the mixing chamber above the level of gravity-accumulated sand therein, substantially as described. 7

2. In a sand blast apparatus, a sand feed box adaptedto receive sand from a super posed hopper, an independent hollow casting arranged within said feed box and forming a mixing chamber, passages opening from the feed box through the sides of said casting to admit sand by gravity to said mixing chamber, together with blast inlet and outlet ports opening through opposite ends 01' said casting above the level of ravityaccumulated sand therein, substantially as described.

3. In a sand blast apparatus, a sand feed box having a receiving chamber open at the top to admit sand from a superposed hopper, an independent hollow casting seated in the lower portion of said chamber and forming the mixing chamber, said casting being open at opposite ends and having side ports for the admission of sand to said mixing chamber by gravity, a blast entry port opening to the mixing chamber above the level of gravity-accumulated sand therein, and opposed thereto, a hose-receiving discharge nozzle, substantially as described.

t. In a sand blast apparatus, a sand feed box having a receiving chamber open at the top to admit sand from a superposed hopper, an independent hollow casting seated in the lower portion of said chamber and forming the mixing chamber, said casting being open at opposite ends and having side ports for the admission of sand to said mixing chamber by gravity, a blast entry port opening to the mixing chamber above the level of gravity-accumulated sand therein, and, opposed thereto, a readily-detachable hose-receiving discharge nozzle bearing against said receiving-chamber casting and serving to hold the latter in position, substantially as described.

5. In a sand blast apparatus, a sand feed boxadapted to receive sand from a superposed hopper, an independent hollow casting arranged within said feed box and forming a mixing chamber, passages opening from the feed box through the sides of said casting to admit sand by gravity to said mixing chamber, together with blast inlet} and outlet ports opening through opposite ends of inulated sand therein, together-With a slide to hold the casting to its seat, substantially valve for controlling the lateral sand-inlet as described. ports to the mixing chamber, substantially In testimony whereof I have signed my as described. 7 name to this specificatici'z, in the presence cf 6. In a sand blast apparatus, a sand feed twcsubscribing Witnesses. box internally recessed to form a seat, a 1101- CHARLES A. DREISBACH. low casting With blast and sand ports resting Witnesses: in said seat, and a discharge nozzle bearing WALTER ABBE, against said casting and secured to said box L. H. G-ROTE. 

